Effect of processing methods on chemical and amino acid Composition of the flours of two winter sorghum Cultivars
Abstract
Grain sorghum is the leading cereal crop in the Sudan, grown in the summer season, and acts as the principal source of energy, protein, vitamins and minerals for the low-income population living in Sudan. To secure the sorghumn grain availability throughout the year, farmers in a rural area of West and South Darfur developed two winter sorghum cultivars known as Abu Ragaba and Abu Kunjara. To date, studies on the nutritional quality of these winter sorghum cultivars are rare. Thus, in this research we examined the effect of fermentation and/or cooking on the chemical composition, amino acid content, and the scores of essential amino acids of the flour of two Sudanese winter season cultivars and one summer season cultivar locally known as Wad Ahmed. The results obtained showed that the cultivars differed significantly (p ≤ 0.05) in nutrients contents. Abu Ragaba and Abu Kunjara had higher ash content (3.74 and 5.15 %, respectively) than Wad Ahmed (1.71%). Abu Kunjara had the highest protein content (19.37%) followed by Wad Ahmed (14.40%). Chemical composition of the cultivars gave inconsistent results after fermentation and cooking. Fermentation increased protein content while reducing the level of some amino acids due to the action of fermenting microorganisms. Cooking of raw and fermented flour had a minor effect on chemical composition. The starch content decreased after fermentation and increased after cooking of raw and fermented samples. Cooking of unfermented and fermented dough increased (p ≤ 0.05) the amino acids content. Although cooking of both raw flour and fermented dough increased lysine score to 14.30, 26.60, and 34.20% of Wad Ahmed, Abu Ragaba, and Abu Kunjara, respectively, it remains the most limiting amino acid followed by sulphur amino acids. Overall, the results demonstrated that fermentation and cooking of winter sorghum grains could improve the nutritive quality of these grains.
